US3395535A - Pneumatic-hydraulic tread brake unit - Google Patents

Pneumatic-hydraulic tread brake unit Download PDF

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Publication number
US3395535A
US3395535A US560559A US56055966A US3395535A US 3395535 A US3395535 A US 3395535A US 560559 A US560559 A US 560559A US 56055966 A US56055966 A US 56055966A US 3395535 A US3395535 A US 3395535A
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US
United States
Prior art keywords
chamber
piston
hydraulic
brake
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US560559A
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English (en)
Inventor
Robert B Morris
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Westinghouse Air Brake Co
Original Assignee
Westinghouse Air Brake Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Westinghouse Air Brake Co filed Critical Westinghouse Air Brake Co
Priority to US560559A priority Critical patent/US3395535A/en
Priority to ES336488A priority patent/ES336488A1/es
Priority to DE19671605304 priority patent/DE1605304A1/de
Priority to FR96590A priority patent/FR1512760A/fr
Priority to BR189003/67A priority patent/BR6789003D0/pt
Application granted granted Critical
Publication of US3395535A publication Critical patent/US3395535A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61H—BRAKES OR OTHER RETARDING DEVICES SPECIALLY ADAPTED FOR RAIL VEHICLES; ARRANGEMENT OR DISPOSITION THEREOF IN RAIL VEHICLES
    • B61H15/00—Wear-compensating mechanisms, e.g. slack adjusters
    • B61H15/0092—Wear-compensating mechanisms, e.g. slack adjusters hydraulic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/58—Combined or convertible systems
    • B60T13/581—Combined or convertible systems both hydraulic and pneumatic
    • B60T13/583—Combined or convertible systems both hydraulic and pneumatic using converters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61H—BRAKES OR OTHER RETARDING DEVICES SPECIALLY ADAPTED FOR RAIL VEHICLES; ARRANGEMENT OR DISPOSITION THEREOF IN RAIL VEHICLES
    • B61H1/00—Applications or arrangements of brakes with a braking member or members co-operating with the periphery of the wheel rim, a drum, or the like
    • B61H1/003—Applications or arrangements of brakes with a braking member or members co-operating with the periphery of the wheel rim, a drum, or the like with an actuator directly acting on a brake head
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/38—Slack adjusters
    • F16D65/72—Slack adjusters hydraulic
    • F16D65/74—Slack adjusters hydraulic self-acting in one direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2125/00—Components of actuators
    • F16D2125/02—Fluid-pressure mechanisms
    • F16D2125/10—Plural pistons interacting by fluid pressure, e.g. hydraulic force amplifiers using different sized pistons

Definitions

  • a tread brake unit for a railway car wheel comprising a lbrake shoe movab-ly carried on a casing and actuated to apply braking force to the wheel by a hydraulic pressure actuated piston, the hydraulic pressure bein-g developed responsive to displacement of ⁇ a plunger intoy ya hydrau-lic pressure chamber at one side of the piston by a second piston subject to compressed air pressure.
  • a sump reservoir containing hydradulic fluid subject to the pressure of the compressed air supplies hydraulic iluid to the hydraulic chamber past a loaded check valve to automatically compensate for wear on the brake shoe, upon withdrawal of the plunger upon relief of the cornpressed air pressure on the second piston.
  • tread brake units have been ernployed on railway cars of the passenger type utilized in rapid transit of subway service.
  • Such tread brake units are of rather large size employing a pivoted actuating lever through which a power cylinder obtains a -orce amplification in applying a braking force to a brake shoe associated with a car wheel.
  • Such tread brake units have embodied therein an automatic slack adjusting mechanism of a complex mechanical type, for maintaining proper clearance between the brake shoe and the tread of the wheel in the brake release position.
  • Such heretofore known tread -brake units are relatively costly and present problems of installation due to space limitations in the car trucks.
  • Tread brake units have been heretofore proposed employing a combination of pneumatic land hydraulic pressure actuated means, but the over-all unit has been relatively large ⁇ and cumbersome in size and present practical diiculties in applying them to modern type railway car trucks.
  • -It is the object of the present invention to provide a relatively small size and lightweight tread brake unit which obtains necessary force amplilication without using a relatively long actuating lever through an arrangement employing a combination of air and hydraulic pressure actuated means and which inherently provides for slack adjustment in a simple manner involving relatively few parts.
  • a novel pneumatic-hydraulic tread brake unit comprising a casing on which a br-ake shoe is movably supported for actuation by Ia hydraulic pressure actuated piston operable in a 'bore in the casing, the hydraulic pressure being developed vand relieved in the hydraulic piston chamber in the bore by a plunger which is reciprocated therein by supply and release of compressed air to a piston member to which the plunger is operatively connected.
  • Hydraulic uid is communicated to the hydraulic piston chamber from an oil sump reservoir, formed in the casing, past a one-way or check valve which traps the oil in the hydraulic piston chamber.
  • Pneumatic pressure is communicated to the top of the oil in the sump reservoir via a chocked communication concurrently with supply of pneumatic pressure to the pneumatic pressure actuated piston to initially -ll the hydraulic piston chamber with oil.
  • the chocked communication so restricts 3,395,535 Patented Aug. 6, V1968 the release of pneumatic pressure from the top of the oil in the sump reservoir, upon release of pneumatic pressure from the piston member actuated thereby, as to cause enough oil to be supplied to the hydraulic piston chamber as the plunger is withdrawn therefrom on brake release as to maintain the brake shoe constantly in cont-act with the tread of the Wheel notwithstanding wear of the brake shoe.
  • Manually operated means is provided for unseating the check valve to permit reverse flow of oil from the hydraulic piston chamber to the sump reservo-ir, as desired, rfor emergency release of the brakes or replacement of the brake shoes.
  • FIG. l shows a side view, partially in section, of a brake unit embodying the invention.
  • FIG. 2 is a -fragmentary view of the main cylinder bore showing the position of the piston and piston rod after the brake shoe has been worn from numerous applications.
  • a pneumatic-hydraulic tread brake unit one of which is provided for each wheel of a railroad car truck is suitably secured, as by bolts and nuts, to the frame of the car truck.
  • the brake unit comprises a casing 1 having a support 2 extending therefrom and an H-shaped or double clevis shaped brake hanger 3 pivotally mounted from said support and carrying a brake head 4 pivoted ⁇ at the lower end of the hanger 3.
  • a brake shoe 5 is secured to the brake head in conventional manner by ⁇ a pin 6. As will be explained more fully hereafter, the brake shoe 5 constantly contacts the tread of a wheel 7.
  • the casing 1 comprises three main secitons, namely a hydraulic power cylinder seciton 8, a pneumatic pressure actuating cylinder section 9 ⁇ and a sump section 10i.
  • the lpower cylinder section 8 comprises a main cylinder bore 11 within the casing having ⁇ -a cylinder head 12 closing the -bore 11 at one end, and the cylinder head 12 having a centrally located bearing 13 located therein.
  • a power piston 14 carrying a packing cup 15 to which a piston rod 16 is colaxially secured as by a nut 17, screwed to the reduced diameter end of the piston rod 16 which is threaded and extended through a central hole in the piston.
  • Piston rod 16 also extends the length of the main cylinder bore 11 ⁇ and through the central bearing 13 of the cylinder head 12 and the rounded end thereof contacts the flat surface heel of the brake head 4.
  • the pneumatic pressure actuating cylinder 9 comprises an actuating plunger or piston 18 which extends through a bore 19 in a w-all 20 into a chamber 21 within the bore 11.
  • the chamber 21 is between the piston 14 and the wall or partition 20.
  • Fluid under pressure from la suitable source is supplied to a pressure chamber 2.5 of the actuating piston 18 at one side of the diaphragm 22 by way of a passage 26 under control of the operator.
  • a chamber 27 is formed on the other side of diaphragm 22 from the chamber 25 between the diaphragm 22 and the wall 20, and is constantly open to atmosphere through a vent port 28.
  • the sump section 10 comprises a sump chamber 29 which communicates with chamber 21 by way of a passage 30 which contains a one-way check valve 31 biased by a spring 32 into seating relation with an annular valve seat 33 for a purpose that will be heerinafter explained.
  • the sump chamber 29 is closed at the top by a cover plate 34 suitably secured in sealed relation to the casing 1 as by a plurality of screws as shown in FIG. 1.
  • the wall of the casing 1 has a port 35 threaded at its outer end and having at its inner end a choke 36. Fluid under pressure is communicated by conventional operator controlled means through the port 35 and choke 36 to the space above the liquid in sump chamber 29 and also to the passage 26 which opens out of the port 35.
  • Hydraulic -uid I is initially supplied to the sump chamber 29 through a filling port 37 in the cover plate 34.
  • the filling port is closed, as by a screw plug 38 secured therein.
  • Plug 38 has a flange portion, the inner face of which seals against the cover plate 34, as by means of an O-ring seal 39, in an annular groove in the underside of the anged portion.
  • bore 40 In the center of the plug 38 is bore 40 through which a release rod 41 extends into sump chamber 29 and the end of which terminates in cl-ose proximity to check valve 31 in the bottom of the sump chamber 29.
  • a -grommet 42 seals the bore 40 against leakage of hydraulic fluid along the rod 41.
  • rod 41 When rod 41 is depressed, i-t engages and uuseats the check valve 31.
  • an inwardly extending overflow prevention cylinder 44 which prevents the liquid rising to the level of the choke 36.
  • the force of the pneumatic pressure on one side of the diaphragm 22 is communicated to the actuating piston 18 which is at rest against piston rod 16 and this force is complemented by the hydraulic fluid under pressure in chamber 21 acting against piston 14 ydue to movement of piston 18 into chamber 21 and the displacement of the iiuid therein proportional to the increased volume of piston 18 within chamber 21.
  • the force kon power piston 14 is thus exerted, by way of piston rod 16, against the brake head 4 for applying the brake shoe on the tread of the wheel 7.
  • brake shoe 5 is normally in contact with the tread of the wheel so that only slight axial movement of the pist-on rod is required to effect exertion of braking force on the wheel.
  • a differential pressure is thus created between sump chamber 29 and chamber 21 which forces the check valve 31 in passage 30 off its seat 33 allowing fluid to flow from said sump chamber 29 into chamber 21 to compensate for space provided by the withdrawal of the piston 18. Accordingly, the hydraulic fluid in chamber 21 causes power piston 14 and piston rod 16 to hold brake shoe 5 in a light-pressure (nonbraking) contact with the tread of the wheel 7. At this time, some clearance between the end of the piston 18 and the piston rod 16 may occur.
  • brake shoe 5 wears and the power piston 14 and the piston rod 16 will, as before, apply a braking force to the brake shoe 5 which remains in contact with the tread of the wheel 7. It will be seen that wear of the brake shoe will be compensated for by the automatic hydraulic slack adjusting action 0i' the hydraulic power section. As wear of the brake shoe S occurs, power piston 14 will move progressively leftward from the position in which it is shown in FIG. 1 to a position such as that illustratively shown in FIG. 2.
  • chamber 21 is automatically filled with hydraulic liquid from sump chamber 29 via check valve 31, each time the lactuating piston is withdrawn from chamber 21 on release of the brakes.
  • chamber 21 is always completely filled with hydraulic liquid lso that as the actuating piston 18 repeatedly moves into chamber 21, it displaces a relatively equal amount of hydraulic fluid each time, thus exerting a substantially uniform hydraulic force on the power piston 14, rod 16 and brake head 4 corresponding to a given liuid pressure in diaphragm chamber 25.
  • the release rod 41 may be operated by depressing it manually.
  • depression of the rod 41 results in equalization of pressure in chambers 21 and 29 ⁇ via the unseated check valve 31, with the result that only a slight amount of force remains on the brake head 4 and shoe 5 via rod 16, to keep the brake shoe 5 in constant contact with tread 7 of the wheel.
  • Fluid pressure braking apparatus comprising:
  • passage means via which to communicate compressed air simultaneously to said reservoir to pressurize the liquid therein and to act on the said another piston means
  • Fluid power brake apparatus as claimed in claim 1, further characterized by manually actuated means for effecting unseating of said one-way valve to effect reverse ow of the fluid from the said chamber to the said reservoir to equalize pressures therein and effect a brake release.
  • Fluid power braking apparatus as claimed in claim 1, further characterized by manually operable stem means, accessible for operation from the exterior of said reservoir and extending through said reservoir, the length of said stem engaging the one-way valve to unseat it upon depression of said stem, and biasing means for returning said stem to a position in which the one-way valve is reseated upon release of operating pressure on the said stem.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Braking Arrangements (AREA)
US560559A 1966-06-27 1966-06-27 Pneumatic-hydraulic tread brake unit Expired - Lifetime US3395535A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US560559A US3395535A (en) 1966-06-27 1966-06-27 Pneumatic-hydraulic tread brake unit
ES336488A ES336488A1 (es) 1966-06-27 1967-02-06 Un aparato de frenado por presion de fluido.
DE19671605304 DE1605304A1 (de) 1966-06-27 1967-02-08 Kombinierte druckluft- und hydraulisch gesteuerte Bremseinrichtung
FR96590A FR1512760A (fr) 1966-06-27 1967-02-27 Dispositif pneumatique-hydraulique de freinage sur jante
BR189003/67A BR6789003D0 (pt) 1966-06-27 1967-04-28 Unidade de freio pneumatico hidraulico de face de rolamento

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US560559A US3395535A (en) 1966-06-27 1966-06-27 Pneumatic-hydraulic tread brake unit

Publications (1)

Publication Number Publication Date
US3395535A true US3395535A (en) 1968-08-06

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ID=24238318

Family Applications (1)

Application Number Title Priority Date Filing Date
US560559A Expired - Lifetime US3395535A (en) 1966-06-27 1966-06-27 Pneumatic-hydraulic tread brake unit

Country Status (5)

Country Link
US (1) US3395535A (es)
BR (1) BR6789003D0 (es)
DE (1) DE1605304A1 (es)
ES (1) ES336488A1 (es)
FR (1) FR1512760A (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4072013A (en) * 1974-10-10 1978-02-07 Aldo Barbareschi Fluid pressure actuated operator cylinder with incorporated stress converter
US4785918A (en) * 1986-03-06 1988-11-22 Iveco Fiat S.A. Pneumo-hydraulic converter for disc brake callipers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2935647C3 (de) * 1979-09-04 1982-03-18 Otto Sauer Achsenfabrik Keilberg, 8751 Bessenbach Schwimmsattel-Teilbelag-Scheibenbremse, insbesondere für Nutzfahrzeuge wie Lastkraftwagen und Anhänger

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2626021A (en) * 1947-08-29 1953-01-20 Louis A Mcalpine Hydraulic link in brake mechanism
US2827766A (en) * 1954-12-09 1958-03-25 Lionel E Weiss Hydro-pneumatic press apparatus
US2926758A (en) * 1957-10-23 1960-03-01 Westinghouse Air Brake Co Hydro-pneumatic type tread brake unit for railway cars

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2626021A (en) * 1947-08-29 1953-01-20 Louis A Mcalpine Hydraulic link in brake mechanism
US2827766A (en) * 1954-12-09 1958-03-25 Lionel E Weiss Hydro-pneumatic press apparatus
US2926758A (en) * 1957-10-23 1960-03-01 Westinghouse Air Brake Co Hydro-pneumatic type tread brake unit for railway cars

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4072013A (en) * 1974-10-10 1978-02-07 Aldo Barbareschi Fluid pressure actuated operator cylinder with incorporated stress converter
US4785918A (en) * 1986-03-06 1988-11-22 Iveco Fiat S.A. Pneumo-hydraulic converter for disc brake callipers

Also Published As

Publication number Publication date
BR6789003D0 (pt) 1973-06-14
ES336488A1 (es) 1968-04-01
FR1512760A (fr) 1968-02-09
DE1605304A1 (de) 1971-03-25

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